    #include <bits/stdc++.h>
    using namespace std;
     
    #define ONLINE_JUDGE
     
    #ifndef ONLINE_JUDGE
    #define dbg(x...) { cerr << "\033[32;1m" << #x << " -> "; err(x); }
    void err() { cerr << "\033[39;0m" << endl; }
    template<typename T, typename... A>
    void err(T a, A... x) { cerr << a << ' '; err(x...); }
    #else
    #define dbg(...)
    #endif
     
    typedef long long LL;
     
    int n;
     
    int main(int argc, char const *argv[])
    {
    	scanf("%d", &n);
    	double ans = 0;
    	for (int i=n; i>=1; --i)
    		ans += 1.0 / i;	
    	printf("%.6lf\n", ans);
    	return 0;
    }